By Ransdell Pierson

NEW YORK, May 15 (Reuters) - Johnson & Johnson's <JNJ.N> experimental drug ustekinumab proved safe and highly effective in controlling psoriasis for a year or longer in two late-stage trials, while requiring injections only once every three months.

The results suggest the medicine could be a good option for the high percentage of patients with the skin disorder who have failed to continue with current treatments, due to their inconvenience or inadequate effectiveness, researchers said.

Findings from the two Phase III trials -- one involving treatment for a year and the other for up to 76 weeks -- were published in the journal Lancet. They bolster similarly favorable data previously reported in shorter-term analyses.

Both studies involved patients with moderate to severe psoriasis, meaning at least 10 percent of their skin had the scaly patches or other hallmarks of the disease which affects up to an estimated 7.5 million Americans.

In the 76-week study, called Phoenix 1, 766 patients were divided into groups that received either 45-milligram or 90-milligram injections of the drug at the start of the trial, at week 4, and then one injection every 12 weeks. Another group received placebo injections.

"Onset of efficacy was rapid, with higher proportions of ustekinumab-treated patients achieving at least 50 percent improvement" in symptoms by week two, researchers said.

Two thirds of those on both doses of the J&J drug experienced at least a 75 percent reduction in their psoriasis symptoms after 12 weeks, compared with only 3.1 percent of those in the placebo group.

At week 40, that magnitude of relief continued among 150 patients in the low-dose group and 172 patients in the high-dose group.

Roughly half of those long-term responders continued with injections of ustekinumab as long-term maintenance treatment, while the other half stopped taking the medicine.

The average symptom relief remained stable to at least week 76 among patients who continued to receive maintenance injections. By contrast, symptom relief began to wane gradually by week 44 in those who discontinued treatment, and accelerated after week 52.

The other Phase 3 trial, lasting 52 weeks and called Phoenix 2, involved 1,230 patients and produced results equally impressive as the companion study.

It determined that 23 percent of patients in the low-dose drug group and 16 percent in the high-dose group achieved less than a 75 percent decrease in symptoms after 28 weeks. These so-called partial responders tended to be heavier patients or have more severe disease.

Putting them all on the higher dose and giving them more frequent injections -- once every 8 weeks instead of every 12 -- led to significant improvement by week 52.

The drug was well tolerated in both studies, with generally mild side effects that did not require adjustments in the medicine, researchers said.

By contrast, current treatments -- including Wyeth's <WYE.N> leading injectable Enbrel, Abbott Laboratories' <ABT.N> injectable Humira and J&J's older Remicade medicine that is given by intravenous infusion -- can increase risk of infection and reactivate tuberculosis.

"Not only does ustekinumab compare favorably with the best available therapies for psoriasis, the maintenance of response between injections every three months also provides a more convenient treatment regimen," said an editorial in the Lancet, citing the two late-stage trials.

J&J is hoping its new drug, formerly known as CNTO-1275, will be approved by the U.S. Food and Drug Administration by September and win European approval early next year. An FDA advisory panel plans to review the medicine on June 17.

Abbott has reported similarly favorable results for its rival experimental psoriasis drug, ABT-874, in a mid-stage trial. But J&J has said it believes its product is several years further along in development.

The new J&J and Abbott medicines work by blocking interleukin-12 and interleukin-23 -- two proteins linked to inflammation in psoriasis and other autoimmune disorders.

Enbrel, Humira and Remicade work by blocking another inflammation-causing protein, called tumor necrosis factor (TNF). (Editing by Tim Dobbyn)

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